Called when user moves over an item or item's icon, handle, badge or count

<div class="definition">
    onClick = function(event)
</div>

You can add event listener during the object creation:

<textarea class="javascript">
let sidebar = new w2sidebar({
    name : 'sidebar',
    nodes: [
        { id: 'id-1', text: 'Level 1' },
        { id: 'id-2', text: 'Level 2' },
        { id: 'id-3', text: 'Level 3' }
    ],
    onMouseEnter(event) {
        console.log(event)
    }
})
</textarea>

or after the object has been created:

<textarea class="javascript">
w2ui.sidebar.on('onMouseEnter', function(event) {
    console.log(event)
})
</textarea>

This event is triggered to show the tooltip over the hangle, icon, badge or count or just catch event when user moves mouse over the
item. You can find out what part of the item is move on if you read `event.detail`, which you can canel and no tooltip (if it is define)
will be show.
<div style="height: 10px;"></div>

The event handler is called before the default action of the event is triggered. You can cancel the default action by calling
<span class="method">event.preventDefault()</span>. To perform an action
after the event is fully processed, define <span class="method">event.onComplete</span> function.
<div style="height: 10px;"></div>
See <a href="utils/events">events</a> page in utilities for more details.